Urticaria (or hives) is a skin condition—commonly caused by an allergic reaction—that is characterized by raised red skin wheals (welts). It is also known as nettle rash or uredo. Hives can be round, or they can form rings or large patches that can occur anywhere on the body, such as the trunk, arms and legs. Wheals (welts), red lesions with a red “flare” at the borders, are another manifestation of hives. Wheals from urticaria can also appear anywhere on the body, including the face, lips, tongue, throat and ears. The wheals may vary in size from about 5 mm (0.2 inches) in diameter to the size of a dinner plate; they typically itch, sting or burn severely and often have a pale border.
One hallmark of hives is their tendency to change size rapidly and to move around, disappearing in one place and reappearing in others, often in a matter of hours. Individual hives usually last two to twenty-four hours. An outbreak that looks impressive, even alarming, first thing in the morning can be completely gone by noon, only to be back in full force later in the day. Very few, if any, other skin diseases occur and then resolve so rapidly.
Treatment of Hives
Hives can be very difficult to treat. There are no guaranteed treatments or means of controlling attacks, and some sub-populations are treatment-resistant, with medications spontaneously losing their effectiveness. It can be difficult to determine appropriate medications since some, such as loratadine, require a day or two to build up to effective levels, and since the condition is intermittent and outbreaks typically clear up without any treatment.
Most treatment plans for urticaria involve being aware of one’s triggers, but this can be difficult since there are several different forms of urticaria and people often exhibit more than one type. Also, since symptoms are often idiopathic, there might not be any clear trigger. If one’s triggers can be identified, then outbreaks can often be managed by limiting one’s exposure to these situations.
The goal of treating most cases of ordinary urticaria is to relieve symptoms while the condition goes away by itself. The most commonly used oral treatments are antihistamines, which help oppose the effects of the histamine leaked by mast cells. The main side effect of antihistamines is drowsiness.
Drug treatment is typically in the form of antihistamines such as diphenhydramine, hydroxyzine, cetirizine and other H1 receptor antagonists. These are taken on a regular basis for a protective effect, lessening or halting attacks. While the disease is obviously physiological in origin, psychological treatments such as stress management can sometimes lessen severity and occurrence. Additionally, methods similar to psychological pain management can be used to shift focus away from the discomfort and itchiness during an attack.
- Many antihistamines are available without prescription, such as diphenhydramine (Benadryl), taken in doses of 25 milligrams and chlorpheniramine (Chlor-Trimeton), taken in a dose of 4 milligrams. These can be taken up to three times a day, but because these medications can cause drowsiness, they are often taken at bedtime. Those who take them should be especially careful and be sure they are fully alert before driving or participating in other activities requiring mental concentration.
- Loratadine (Claritin, 10 milligrams) is available over-the-counter and is less likely to cause drowsiness. Also approved for over-the-counter use is cetirizine (Zyrtec, 10 milligrams), which is mildly sedating. Some antihistamines come bundled with decongestant medication (Claritin-D, Zyrtec-D). The decongestant component is not needed to treat hives.
- Antihistamines that require a prescription include hydroxyzine (Atarax, Vistaril) and cyproheptadine, both of which tend to cause drowsiness. Prescription antihistamines that cause little sedation are fexofenadine (Allegra) and levocetirizine (Xyzal). Sometimes physicians combine these with other types of antihistamines called H2 blockers, such as ranitidine (Zantac) and cimetidine (Tagamet).
- The H2-receptor antagonists such as cimetidine and ranitidine may help control symptoms either prophylactically or by lessening symptoms during an attack. When taken in combination with an H1 antagonist, it has been shown to have a synergistic effect which is more effective than either treatment alone. The use of ranitidine (or other H2 antagonist) for urticaria is considered an off-label use, since these drugs are primarily used for the treatment of peptic ulcer disease and gastroesophageal reflux disease.
For your information, this antihistamine list is in no way exhaustive; there are many more medications out there for hives patients to try out. Physicians individualize treatment plans to suit specific patients and modify them depending on the clinical response.
- Tricyclic antidepressants such as doxepin are also often potent H1 and H2 antagonists and may have a role in therapy, although side effects limit their use. For very severe outbreaks, an oral corticosteroid such as Prednisone is sometimes prescribed. However, this form of treatment is controversial because of the extensive side effects common with corticosteroids and as such is not a recommended long-term treatment option.
- Oral steroids (Prednisone, Medrol) can help severe cases of hives in the short-term, but their usefulness is limited by the fact that many cases of hives last too long for steroid use to be continued safely. Other treatments have been used for urticaria as well, including montelukast (Singulair), ultraviolet radiation, antifungal antibiotics, agents that suppress the immune system and tricyclic antidepressants such as amitriptyline (Elavil, Endep), nortriptyline (Pamelor, Aventyl) and doxepin (Sinequan, Adapin). Evidence to support the benefit of such treatments is sparse. In ordinary cases, they are rarely needed.
- Topical therapies for hives include creams and lotions which help numb nerve endings and reduce itching. Some ingredients which can accomplish this are camphor, menthol, diphenhydramine and pramoxine. Many of these topical preparations require no prescription. Cortisone-containing creams (steroids), even strong ones needing a prescription, are not very helpful in controlling the itch of hives.
To know exactly what kind of hives you have, or to learn more about research into the immune basis of hives or about rarer forms of this condition, you should consult your physician. It is important, however, to keep in mind that most cases of this common disorder represent either ordinary urticaria or physical urticaria, which are annoying but not serious or allergic, and almost always temporary.
Causes of Hives
Hives are generally caused by direct contact with an allergenic substance or an immune response to food or some other allergen, but can also appear for other reasons, notably emotional stress. The rash can be triggered by quite innocent events, such as mere rubbing or exposure to cold.
Hives are also produced by histamine and other compounds released from cells called mast cells, which are a normal part of skin. Histamine causes fluid to leak from the local blood vessels, leading to swelling in the skin.
Hives are very common. Although they can be very annoying, they usually resolve on their own over a period of weeks and are rarely medically serious. Some hives are caused by allergies to such things as foods, medications and insect stings, but the large majority of cases are not allergic, and no specific cause for them is ever found.
Although patients may find it frustrating not to know what has caused their hives, maneuvers like changing diet, soap, detergent and makeup are usually not helpful in preventing hives and are for the most part unnecessary.
In rare cases (some hereditary, others caused by bee stings or drug allergy), urticaria and angioedema are accompanied by shock and difficulty of breathing. This is called anaphylaxis. Ordinary urticaria may be widespread and disturbing to look at, but the vast majority of cases do not lead to life-threatening complications.
Types of Hives
- Ordinary Urticaria flares up suddenly (and usually) for no specific reason. Welts appear, often in several places. They flare, itch, swell and go away in a matter of minutes to hours, only to appear elsewhere. This sequence may go on from days to weeks. Most episodes of hives last less than six weeks. Although that cutoff point is arbitrary, hives that last more than six weeks are often called “chronic.”
- Chronic Urticaria refers to hives that persists for 6 weeks or more. There are no visual differences between acute and chronic urticaria. Some of the more severe chronic cases have lasted more than 20 years. Allergy testing and laboratory tests are hardly ever useful in such cases.
- Drug-induced Urticaria has been known to result in severe cardiorespiratory failure. The anti-diabetic sulphonylurea glimepiride (trade name Amaryl), in particular, has been documented to induce allergic reactions manifesting as urticaria. Other cases include dextroamphetamine, aspirin, penicillin, clotrimazole, sulfonamides and anticonvulsants.
- Acute Urticaria usually shows up a few minutes after contact with the allergen and can last a few hours to several weeks. Food allergic reactions typically fit in this category. Common causes of reaction include consumption of shellfish, nuts, eggs, fish, acid derivatives, dye or a combination of these.
- Physical Urticaria refers to hives produced by direct physical stimulation of the skin. By far the most common form is “dermographia,” which literally means “skin writing.”
Other forms of physical hives are much less common. Triggers for these include cold, water and sunlight. As such, physical urticarias are often categorized into the following:
- Aquagenic: Reaction to water (rare).
- Cholinergic: Reaction to body heat, such as when exercising or after a hot shower.
- Cold (Chronic cold urticaria): Reaction to cold, such as ice, cold air or water.
- Delayed Pressure: Reaction to standing for long periods of time or reaction to panty or thong bands, bra-straps and belts.
- Dermatographic: Reaction when skin is scratched (very common).
- Heat: Reaction to hot food or objects (rare).
- Solar: Reaction to direct sunlight (rare).
- Vibration: Reaction to vibration (rare).
- Adrenergic: Reaction to adrenaline/noradrenaline (extremely rare).
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